feat(linter): eslint-plugin-unicorn require-number-to-fixed-digits-argument

crates/oxc_linter/src/rules.rs

@@ -148,6 +148,7 @@ mod unicorn {
     pub mod no_unnecessary_await;
     pub mod prefer_array_flat_map;
     pub mod prefer_logical_operator_over_ternary;
+    pub mod require_number_to_fixed_digits_argument;
     pub mod switch_case_braces;
     pub mod text_encoding_identifier_case;
     pub mod throw_new_error;
@@ -263,6 +264,7 @@ oxc_macros::declare_all_lint_rules! {
     unicorn::no_unnecessary_await,
     unicorn::prefer_array_flat_map,
     unicorn::prefer_logical_operator_over_ternary,
+    unicorn::require_number_to_fixed_digits_argument,
     unicorn::switch_case_braces,
     unicorn::text_encoding_identifier_case,
     unicorn::throw_new_error,

crates/oxc_linter/src/rules/unicorn/require_number_to_fixed_digits_argument.rs

@@ -0,0 +1,133 @@
+use oxc_ast::{ast::Expression, AstKind};
+use oxc_diagnostics::{
+    miette::{self, Diagnostic},
+    thiserror::Error,
+};
+use oxc_macros::declare_oxc_lint;
+use oxc_span::{GetSpan, Span};
+
+use crate::{context::LintContext, fixer::Fix, rule::Rule, AstNode};
+
+#[derive(Debug, Error, Diagnostic)]
+#[error("eslint-plugin-unicorn(require-number-to-fixed-digits-argument): Number method .toFixed() should have an argument")]
+#[diagnostic(severity(warning), help("Pass an argument to .toFixed() method."))]
+struct RequireNumberToFixedDigitsArgumentDiagnostic(#[label] pub Span);
+
+#[derive(Debug, Default, Clone)]
+pub struct RequireNumberToFixedDigitsArgument;
+
+declare_oxc_lint!(
+    /// ### What it does
+    /// Enforce using the digits argument with Number.toFixed()
+    ///
+    /// ### Why is this bad?
+    /// It's better to make it clear what the value of the digits argument is when calling Number.toFixed(),
+    /// instead of relying on the default value of 0.
+    ///
+    /// ### Example
+    /// ```javascript
+    /// // Pass
+    /// number.toFixed(0);
+    /// number.toFixed(2);
+    ///
+    /// // Fail:
+    /// number.toFixed();
+    /// ```
+    RequireNumberToFixedDigitsArgument,
+    correctness
+);
+
+impl Rule for RequireNumberToFixedDigitsArgument {
+    fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
+        let AstKind::CallExpression(expr) = node.kind() else {
+            return;
+        };
+
+        if !expr.arguments.is_empty() || expr.optional {
+            return;
+        }
+
+        if let Some(member) = expr.callee.get_member_expr() {
+            if let Expression::NewExpression(_) = member.object() {
+                return;
+            }
+
+            if member.optional() || member.is_computed() {
+                return;
+            }
+
+            if let Some(property_name) = member.static_property_name() {
+                if property_name == "toFixed" {
+                    let parenthesis_span = Span { start: member.span().end, end: expr.span.end };
+
+                    ctx.diagnostic_with_fix(
+                        RequireNumberToFixedDigitsArgumentDiagnostic(parenthesis_span),
+                        || {
+                            let modified_code = {
+                                let mut formatter = ctx.formatter();
+
+                                let mut parenthesis_span_without_right_one = parenthesis_span;
+                                parenthesis_span_without_right_one.end -= 1;
+
+                                let span_source_code = parenthesis_span_without_right_one
+                                    .source_text(ctx.source_text());
+
+                                formatter.print_str(span_source_code.as_bytes());
+                                formatter.print_str(b"0)");
+
+                                formatter.into_code()
+                            };
+
+                            Fix::new(modified_code, parenthesis_span)
+                        },
+                    );
+                }
+            }
+        }
+    }
+}
+
+#[test]
+fn test() {
+    use crate::tester::Tester;
+
+    let pass = vec![
+        "number.toFixed(0)",
+        "number.toFixed(...[])",
+        "number.toFixed(2)",
+        "number.toFixed(1,2,3)",
+        "number[toFixed]()",
+        "number[\"toFixed\"]()",
+        "number?.toFixed()",
+        "number.toFixed?.()",
+        "number.notToFixed();",
+        "new BigNumber(1).toFixed()",
+        "new Number(1).toFixed()",
+    ];
+
+    let fail = vec![
+        "const string = number.toFixed();",
+        "const string = number.toFixed( /* comment */ );",
+        "Number(1).toFixed()",
+        "const bigNumber = new BigNumber(1); const string = bigNumber.toFixed();",
+    ];
+
+    let fix = vec![
+        ("const string = number.toFixed();", "const string = number.toFixed(0);", None),
+        (
+            "const string = number.toFixed( /* comment */ );",
+            "const string = number.toFixed( /* comment */ 0);",
+            None,
+        ),
+        ("Number(1).toFixed()", "Number(1).toFixed(0)", None),
+        (
+            "const bigNumber = new BigNumber(1); const string = bigNumber.toFixed();",
+            "const bigNumber = new BigNumber(1); const string = bigNumber.toFixed(0);",
+            None,
+        ),
+    ];
+
+    Tester::new_without_config(RequireNumberToFixedDigitsArgument::NAME, pass, fail)
+        .expect_fix(fix)
+        .test_and_snapshot();
+}

crates/oxc_linter/src/snapshots/require_number_to_fixed_digits_argument.snap

@@ -0,0 +1,33 @@
+---
+source: crates/oxc_linter/src/tester.rs
+expression: require_number_to_fixed_digits_argument
+---
+  ⚠ eslint-plugin-unicorn(require-number-to-fixed-digits-argument): Number method .toFixed() should have an argument
+   ╭─[require_number_to_fixed_digits_argument.tsx:1:1]
+ 1 │ const string = number.toFixed();
+   ·                              ──
+   ╰────
+  help: Pass an argument to .toFixed() method.
+
+  ⚠ eslint-plugin-unicorn(require-number-to-fixed-digits-argument): Number method .toFixed() should have an argument
+   ╭─[require_number_to_fixed_digits_argument.tsx:1:1]
+ 1 │ const string = number.toFixed( /* comment */ );
+   ·                              ─────────────────
+   ╰────
+  help: Pass an argument to .toFixed() method.
+
+  ⚠ eslint-plugin-unicorn(require-number-to-fixed-digits-argument): Number method .toFixed() should have an argument
+   ╭─[require_number_to_fixed_digits_argument.tsx:1:1]
+ 1 │ Number(1).toFixed()
+   ·                  ──
+   ╰────
+  help: Pass an argument to .toFixed() method.
+
+  ⚠ eslint-plugin-unicorn(require-number-to-fixed-digits-argument): Number method .toFixed() should have an argument
+   ╭─[require_number_to_fixed_digits_argument.tsx:1:1]
+ 1 │ const bigNumber = new BigNumber(1); const string = bigNumber.toFixed();
+   ·                                                                     ──
+   ╰────
+  help: Pass an argument to .toFixed() method.
+
+